Polk Magnifi Max (SR) cannot detect 5GHz

Hi,
Im having issues with my newly bought Magnifi Max SR as I cannot connect to 5Ghz wifi.

My router is ASUS AC88U and other devices such as my Google hub , my phone, etc. can connect to the 5Ghz band. Ive already got my router to have different SSIDs for 2.4Ghz and 5Ghz . If its worth noting (cause I've read in the manual that 5Ghz is supported in selected countries only - but im not sure why this is related) - I live in Philippines.

Any help?

Thanks!